It's an alternative to Radio, and an alternative to YouTube for celebs who don't want the production hassle.
Also, you need enough momentum to convince advertisers as well.
It was a slow and bumpy ride but I think that all the pieces are now in place and so we'll see a lift.
My belief is that this is going to be more or less permanent a secular shift, not a pop, because the nature if it is just not very pop-sugar or hype-ish. NPR listeners are not faddish.
Obviously, content is still going to be important, and you can't just slap up BuzzFeed crap. NPR has a loyal following. Joe Rogan makes basically the perfect pop-culture podcast. Celebs have star power and invite other celebs for their love-ins. There's some popular specific podcasts on things like the 'Roman Empire'.
I don't think it will be a huge boon and I don't see any massive companies or takeovers, but it's a real shift.